Simon Lewis has been a human and a vampire, and now he is becoming a Shadowhunter. The events of City of Heavenly Fire left him stripped of his memories, and Simon isn't sure who he is anymore. So when the Shadowhunter Academy reopens, Simon throws himself into this new world of demon hunting, determined to find himself again. Whomever this new Simon might be. But the Academy is a Shadowhunter institution, which means it has some problems.

When fifteen-year-old Clary Fray heads out to the Pandemonium Club in New York City, she hardly expects to witness a murder - much less a murder committed by three teenagers covered with strange tattoos and brandishing bizarre weapons. Then the body disappears into thin air. It's hard to call the police when the murderers are invisible to everyone else and when there is nothing - not even a smear of blood - to show that a boy has died. Or was he a boy?

Cordelia Carstairs is a Shadowhunter, a warrior trained since childhood to battle demons. When her father is accused of a terrible crime, she and her brother travel to London in hopes of preventing the family’s ruin. Cordelia’s mother wants to marry her off, but Cordelia is determined to be a hero rather than a bride. Soon Cordelia encounters childhood friends James and Lucie Herondale and is drawn into their world of glittering ballrooms, secret assignations, and supernatural salons, where vampires and warlocks mingle with mermaids and magicians.

The Lightwoods, the Shadowhunters who run the New York Institute, are expecting a new addition to their family: the orphaned son of their father’s friend, Jace Wayland. Alec and Isabelle aren’t too sure they want a new brother, and their parents are not assuaging their fears, too occupied with the dark news that Raphael Santiago, second-in-command of the New York vampire clan, has brought from the Shadow Market.

All Magnus Bane wanted was a vacation - a lavish trip across Europe with Alec Lightwood, the shadowhunter who against all odds is finally his boyfriend. But as soon as the pair settles in Paris, an old friend arrives with news about a demon-worshiping cult called the Crimson Hand that is bent on causing chaos around the world. A cult that was apparently founded by Magnus himself. Years ago. As a joke. Now, Magnus and Alec must race across Europe to track down the Crimson Hand and its elusive new leader before the cult can cause any more damage.